Moisture indicator for webs



May 16 1950 l JQs. sENEY 2,508,045r

IOISTURE INDICATOR FOR WEBS Filed oct. a, 194e ssneets-sneet 1` IN V EN TOR. dom/ f 55h/Ey A TTORNE X May 16, 1950 v J, s. sENl-:Y 2,508,045

MOISTURE INDICATOR FOR WEBS Filed oct. e, 194e i y 5 sheets-sheet 2 I N VEN TOR. l/OHN 5. `.S2-N5 Y A TToRN/L'X May 16, 195o Fiied oct. 8, 194e `.1. s. sENEY 2,508,045

MOISTURE INDICATOR FOR WEBS 5L Sheets-Sheet 3 INVENroR. dow/w52l 54m/Ey ATTORNEY May 16, 195o J. s. SENEY 2,508,045

, MOISTURE INDICATOR FOR WEBS Filed Oct. 8, 1946 5 Sheets-Sheet'4 @ya .n @ya llllllllllllll m L IIIIIIIIHHH llllllllilll IN VEN TOR.

A TTORNE Y May 16, 1950 J. s. sENEY MOISTURE INDICATOR FOR WEBS Filed Oct. 8, 1946 5 Sheets-Sheet 5 NSM@ a a A TTRNE Y Patented Mey 16, 195o UNITED STATES PATENT OFFICE MOISTURE INDICATOR FOB WEBS John S. Seney, Richmond, Va., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., acorporation of Delaware Application october s, 194s, semi No. 701,954

13 claims. (ci. ris- 183) This invention relates to moisture indicators for traveling webs, and more particularly to a device for measuring and integrating the total moisture content of each run over a predetermined period of time, and, in addition, for indicating the instantaneous moisture content at all times during the run. The invention is applicable to slashers or to webs of cellulosic materials,'the moisture content of which is to be controlled.

An object of the invention is to provide a device of the above type which may be readily installed and operated on commercial slashers or the like.

Another object is to provide an electrical measuring device of the above type which is responsive to the electrical resistance of the web.

Another object is to provide a. device of the above type which measures both the instantanecus resistance and the average resistance over a period of time.

Another object is to provide a device of the above type which does not require special operating skill for its use.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

In accordance with the present invention, a continuous measurement is made of the electrical resistance of a portion of the web, such as the thread sheet of the slasher, which in turn is a function of its moisture content. For this purpose, the entire thread sheet of the Slasher is passed between a pair of stainless steel rolls located behind the last drier can. The rolls are connected in an electrical circuit with a condenser which is successively charged and discharged at a rate dependent upon the electrical resistance of the portion of the thread sheet extending between the rolls. An electrical counter means is provided for counting the number of times the condenser is charged and discharged during a predetermined period of time, this number representing a measure of the total moisture content. Means is also provided for measuring the charging time of the condenser and indicating the same on a suitable scale which is graduated directly to read moisture content. Means may also be provided to actuate a signalling or control device when the variation in moisture content exceeds predetermined limits.

Although the novel features which are believed to be characteristic of this invention are pointed fout more particularly in the claims appended hereto, the nature of the invention will be better understood by referring to the following descrip- 2 tion, taken in connection with the accompanying drawings in which a specific embodiment thereof has been set forth for purposes of illustration.

In the drawings:

Figure 1 is a front elevation of the moisture indicating instrument;

Figure 2 is an end elevation taken from the right hand side of Figure 1;

Figure 3 is an end elevation taken from the left hand side of Figure 1;

Figure 4 is a section taken on the line 4-4 of Figure 2;

Figure 5 is a top plan view of the instrument;

Figure 6 is a vertical section taken on the line 6 6 of Figure 5; and .Y

Figure '7 is a schematic diagram showing the electrical circuits involved.

Referring first to Figures 1 to 6, the electrical timing instrument isshown as comprising an electric clock motor I0 driving a gear II which is connected to a gear I2 forming one side of a dierential. The gears II and I2 are journalled for free rotation on a shaft I3. A gear Il journalled on the shaft I3 constitutes the other side of the differential and carries a drum II which is engaged by a brake I6 to prevent the drum I5 and gear I4 from turning. The differential cage comprises a pinion I'I meshing with the gears I2 and I4 and carried on a shaft Il which is pinned to the shaft I3 to drive the same. The shaft I3 drives a shaft 20 through a gear train 2|. The shaft 20 carries a, driving arm 22 and is provided with a spring 23 which resets the driving arm 22 to zero position when the brake I6 is released. l

With the brake I6 engaging the drum I5 to lock the gear I4 against turning, the motor Il drives gear I2 and pinion I'I which rotates about the stationary gear Il and drives the shaft I3 which, in turn, through the gear train 2|, drives the arm 22. The arm 22 continues to be driven while the brake i6 is in locked position. When the brake I6 is released, however, the gear I4 is free to rotate as an idler gear and is driven by the pinion I'I without causing the latter to rotate about the periphery thereof. Hence, the shaft I3 is no longer driven by the pinion I1 but is free to rotate, and may be rotated in the opposite direction by the spring 23 to return the arm 22 to its zero position.

The brake I6, as shown in Figure 4, comprises a brake shoe 25 which engages the drum I5 and is mounted upon an arm 25, pivoted on a pin 21. The arm 26 carries a bracket 28 to which an the driving arm 22.

3 armature 29 is attached. The amature 28 is associated with the magnetic circuit oi' .an electromagnet 38 having a winding 3| which is arranged to attract the armature 28 and set the brake shoe 25 against the drum l5 when the electromagnet 38 is energized.

The arm 26 also carries a finger 33 which engages the operating lever 34 of a microswitch 35 in a manner to close the switch contact when the electromagnet 38 is deenergized and the finger 33 is retracted to the position shown, but to open the microswitch contact when the electromagnet 38 is energized to set the brake shoe 25 against the drum and to cause the arm 26 to pivot about the pin 21 so that the finger 33 presses upwardly against the switch lever 34. The purpose of the switch 35 will be explained in connection with Figure 7.

A contact arm 48 (Figures 1 and 6) carrying a pair of contacts 4| is journaled about the shaft 28 and is normally urged to zero position by a spring 42. A member 43 acts as a stop to limit the opening of the contacts 4|. A lip 44 carried by the driving arm V22 engages one side of the contacts 4|, which closes the contacts 4| when the driving arm 22 reaches a position to register with the Contact arm 48. The contact arm 48 carries a pointer 45 registering with a dial 46 which may be marked to read directly in percentage moisture content. The arm 40 also carries a bracket 48 to which a brake member 41 is attached. The brake member 41 engages an arcuate brake shoe 58 which is pivoted at 5| at one end and, at its other end, carries an armature 52 (Figures l and 2) which forms a part of the magnetic circuit of an electromagnet 53 having a winding 54. When energized, the electromagnet 53 attracts the armature 52 and raises the brake shoe 58 from the brake member 41, thereby allowing the spring 42 to turn the arm 48 to the left until it engages the driving arm 22 or reaches its zero position. With the electromagnet 53 de-energized, the brake shoe 50 rests upon the brake member 41 and exerts suificient friction to prevent the arm 48 from being returned due to the action of the spring 42. The drag exerted by the brake shoe 58 is insufficient, however, to prevent the arm 40 from being driven in a clockwise direction, as seen in Figure 1, by The arm 40 is thus retained in its driven position by the brake shoe 58 when the driving arm 22 is reset to zero.

The arm 48 also carries a cam 68 (Figures 1 and 2) which is set to actuate a double throw switch 6| having an arm 62 and contacts 63 and 64 which are selectively closed in accordance with the position of the arm 62. The contacts 63 and 64 are actuated in accordance withthe position of the contact arm 48 and are arranged to be selectively closed when the position of the arm 48 represents an excessive moisture variation.

Referring to Figure 7, the electrical system is shown as supplied from a power source including lines 88 and 8| and controlled by a switch 82. The lines 80 and 8| are connected to the primary 83 of a transformer 84 having a pair of secondary sections 85 and 86. One end of the secondary 85 is connected by a line 81 to the cathode 88 of a space discharge rectier tube 89, the anode 98 of which is connected by a line 9| to a condenser 92, thence by a line 93 to the common point of the secondary sections 85 and 86. A potentiometer 94 is connected across the condenser 92. The tube '89 constitutes a rectifier which is arranged to cause a unidirectional current ilow through the potentiometer I4 to develop a potential drop thereacross. The condenser 82 serves to smooth out the voltage variations and produce a substantially uniform potential drop across the potentiometer.

The secondary section 86 is connected to a condenser 88 and thence to the anode 88o! a space discharge tube |88, which may be of the pliotron type, and is provided with a grid |8| and a cathode |82. A condenser |83 is connected between the grid |8| and cathode |82. The cathode side of the condenser |83 is connected by a line |84 to the return line 83. The grid side of the condenser |83 is-connected by a line |85 to a slasher roller |86. The variable tap |81 of the potentiometer 84 is connected by a line |88 to a contact |89 of a relay ||8 having an energizing coil I An arm ||2 which cooperates with the contact |89 is connected by a lead ||3 to one side of a jack |I4, the other side ot which is connected by a line ||5 to a second Slasher roll ||6. The slasher rolls |86 and ||8 are positioned beyond the last drier can of the Slasher and are so arranged that the entire thread sheet is passed between the two rolls so that a circuit is established between the rolls due to the conductivity of the intervening portion of the thread sheet.

A relay coil |28 is connected across the condenser 88. The coil |28 actuates an armature |2| which, in turn, actuates an arm |22 which is normally closed against a contact |23. The arm |22 and Contact |23 are connected by lines |24 and |25 respectively across the condenser |83.

In the operation of the circuit thus far described, a potential is applied from the tap |81 of the potentiometer 94, through contact |89 and arm ||2 (when closed) and through jack ||4 to the roll ||6, thence through the slasher thread |26 to the roll |86 and through line |85 to condenser |83. The other side of condenser 83 is connected to the potentiometer 84 by line |84, thus completing the condenser-charging circuit. Current owing from the secondary 86, through tube lou and the con izo, holds the Contact Iza open. The condenser |83 continuously charges in a direction to make the grid |8| of the tube |88 negative. When the charge on the condenser |83 reaches a value such that the grid |8| is biased to its cut-off point, the tube |88 becomes non-conductive, thereby interrupting the current ilow through the relay winding |28 and releasing the armature |2|. This closes the contact |23 and short-circuits the condenser |83 to drain the negative charge therefrom and allow the grid |8| to return to its normal potential. The tube |88 thereupon again becomes conducting and the cycle is repeated. The condenser I 83 repeatedly charges to the cut-ofi voltage and is discharged by the de-energization of the relay coil |28 in a cycle, the frequency of which is dependent upon the rate of charge of the condenser |83.

It will be noted that the rate at which the condenser |83 charges is dependent upon the resistance of the thread sheet between the rolls |86 and ||6 which, as previously pointed out, is a function of the moisture content of the thread'. This cycle may take, for example, ten seconds with a normal moisture content.

It will be evident from the above that, by counting the number of charges and discharges over a predetermined period of time, an integrated value of the moisture content over that interval may be obtained. Also. by timing the rate of charge of the condenser |33, an instantaneous value of the moisture content will be obtained. This is accomplished by the reminder of the circuit of Figure 7 to be described.

A step-by-step relay |30 is provided with a ratchet |3| actuated by an armature |32 and a relay coil |33 which is shunted by a condenser |34. The ratchet mechanism drives a rotor |35 having a plurality of bosses |36 thereon which are adapted to actuatea switch arm |31. In one position, the switch arm |31 closes contacts |33 and |33, and in the other position contacts contact |40. The ratchet mechanism |3| is so designed that two operations of the ratchet are required to shift the rotor |35 from the position in which one boss |36 actuates the arm 31 to a position in which the arm |31 has been released and again actuated by the next boss |33. Such a step-by-step relay may be of any standard construction.

A counter |45 is provided with an actuating coil |46 which actuates the counter register |41 and with a reset'button |43 which is normally held outward by a spring |43, but is pushed inwardly against the force of the spring |43 to reset the counter. The reset button |43 actuates an arm |50 which normally closes a contact |5| but automatically opens the contact when the knob |43 is pressed inwardly for resetting the counter.

A timer |55 is provided, which is similar to the timer shown in Figures 1 to 6, with the cam 63, brake shoe 50, and switch 35 omitted. The timer |55 comprises the usual clock motor operated by a coil |56 and a clutch coil |51 which is similar to the coil 3| of the timer' illustrated in Figures 1 to 6, and controls the operation of the driving arm. The timer contact |58, carried by a contact arm, is normally closed but is arranged to be opened when the driving arm oi the timer engages the contact arm. The contact arm in this case is pre-set for the time it is desired for the timer to operate.

A line |65 is connected by a line |66 to the supply line 30. This line is connected through a high speed switch |61 to the relay coil ill, the return connection being grounded. The high speed switch |61 constitutes a centrifugal switch which is arranged to be closed when the Slasher is operating at normal speed but to be opened when the slasher has been stopped. Hence, the relay coil 5H is energized during such times as the slasher may b'e running. Energization of the coil iii closes the contact |03, as previously described, to supply current to the slasher rolls |06 and IIB. It also closes arms |63 against contact |63. Actuation of the switch |61 also closes the circuit to clock coil |56 through a line i110. Hence, the clock motor |56 likewise operates only during the time that the slasher is running. Test jack. |1| is connected across the switch |61 to permit the system to be checked when the Slasher is stopped and the switch |61 is open.

v 'Ihe armature |2| of the relay coil |20 actuates arm |12 to close a contact |13. The contact |13 is connected by a line |14 to a variable resistor |15, thence by a line |16 to one side of the relay coil |33. 'I'he other side of the relay coil |33 is connected by line |11 to the supply line |65. Hence, the relay coil |33 is energized once each time the coil |20 is operated and the contact |33 is closed at every other operation of the coil |20.

The arm |31 oi the ratchet relay is connected asoaou by a une m to the supply une m. The contact |33 is connected' by a line |3| to the counter coil |46, thence by a lin'e |32 to the normally closed contact |53 oi the timer |55. The arm |53 of the timer |55 is connected by a line |33 to the normally closed contact |5| oi' the counter, the arm |50 oi which is grounded by a line |34. Hence, closing oi the contact |33 completes the circuit through the counter coil |46 provided the contacts |53 and |5| are closed and causes the counter coil |43 to register every other actuation of the coil |20.

,When the timer |55 has operated a suilicient period of time for its driver arm to engage the contact arm and open the contact |53, the counter coil |46 is de-energized and no further actuations of thecoil |20 are registered on the counter register |41. The register then indicates half the total number of actuations oi the coil |20, which in turn represents half the total number oi' charges applied to the condenser |03 during the timed period. By referring to a suitable chart. the integrated moisture content for the period may be noted. 'I'his period may, for example, represent the normal running time of a slasher beam, for example 2 hours.

After the reading of the counter |45 has been noted or when a new slasher beam is placed on the machine, the device may be reset by pushing the reset button |48, thereby resetting the counter register |41 and opening the contact |5|. Opening the contact |5| breaks the circuit through the clutch coil |51 of the timer and causes the timer to be reset to zero. When the reset button |48 is released, contact |5| is again closed and lie counter is ready for another cycle of operaion.

For timing the interval between every other actuation of the coil |20, a second timer |30 is em ployed, which is of the type shown in Figures 1 to 6, and previously described. This timer comprises the clock motor coil i0 which is connected by a line |3| to switch |32 and by line |33 to the arm 63 of the relay H0, and thence through contact |63 of the relay i l0 to ground. The other end of the clock coil i0 is connected by line |34 to a normally closed contact |35 of a relay |36 having an actuating coil |31. The contact |35 l engages an arm 593 which is connected by a line- |93 to the supply line |65. Hence, the clock coil is energized through the back contact |35 whenever the relay |36 is cie-energized and the relay H0 is energized, which is the normal operating condition. rihe contact i 35 is also connected by a line 200 and line 20:1 to the clutch coil 3| of the timer |30 and through lines 200 and 202 to the contact |40 of the ratchet relay |30. it will be noted that the clutch coil 3| and the clock coil |0 are normally supplied through the contact |35 when the latter is closed. However, when the contact |35 is opened and the contact |40 is closed, the above coils are supplied through the contact |40.

Contact |33 is connected by a lead 203 to an arm 204 of the relay |36 which normally engages contact 205. The contact 205 is connected by a line 206 to the brake release coil 54 of the timer |30.

Contacts 63 and 64 of the timer |30 are connected by lines 201 and 233 to control lines 203 and 2|0 respectively and to a pair of signal lights 2|| and 2|2 respectively. The signal lights 2|| and 2|2 are shown as `connected through a variable resistor 2|3 and line 2|4 to the Supply line The microswitch 35 is provided with a contact 220 which is connected by a line 22| to a contact 222 which engages the arm |93 when the relay |96 is actuated. The coil |01 of the relay |98 is connected by a line 223 to the contacts 4| and thence by a lead 224 to the arm 225 of the microswitch.

The operation of the timer |90 is as follows: The clock motor I of the timer |90 is energized whenever the relay coil is energized and contact |40 is closed, that is whenever the slasher is running. Hence, the clock operates to advance the driving arm 22 (Figure 1) whenever the slasher is running and contact 40 is closed and the clutch coil 3| is energized.

With the relay |91 de-energized, the clock motor 0 and the clutch coil 3| are supplied through the contact |85 as above described. When the ratchet relay |30 is advanced to close the contact |40, the clock motor coil I0 and clutch coil 3| are energized through the contact |40 regardless of whether or not the contact |95 has meanwhile opened.

When the ratchet relay has advanced one step to again open the contact |40 and close the contact |38, the brake release coil 54 is energized through the contact |38 and the contact 205 of the relay |96, thereby elevating the brake shoe 50 and allowing the contact arm 40 to be returned in a counterclockwise direction by the action of the spring'l2 until it engages the driving arm 22, thereby momentarily closing the contact 4|. Closing the contact 4| energizes the relay |96, thereby opening the contact 205 and de-energizing the coil 54 to allow the brake shoe 50 to again engage the brake member 41 and hold the arm 40 in its then position. Actuation of the relay also opens the contact |95 and closes the contact 222. Opening the contact |95 interrupts the circuit through the clock motor i0 and through the clutch coil 3|, thereby releasing the clutch coil and allowing the arm 22 of the timer |90 to be returned to zero position by the spring 23. Movement of the arm 22 away from the contact arm 4|) allows the contacts 4| to again open. At the same time, release of the coil 3| closes the microswitch 35 which acts as holding contact on the relay |96 to hold the same in actuated position.

It will be noted that the pointer 45 is now held at a position which corresponds to the maximum clockwise position of the driving arm 22 before the timer was reset.

At the next step oi the ratchet relay |30, contact |40 is closed thereby again energizing the clock motor |0 and the clutch coil 3|. Energization of the clutch coil 3| breaks the contact of the microswitch and releases the relay |96.

It will be noted that if the succeeding cycle period is shorter, the contact |38 closes first,v

thereby releasing the indicator arm 40 and allowing the same to drop against the driver arm 22, as above described. Hence, the indicator arm 40 always indicates the length of the last cycle or the time required for the next to the last charge of the condenser |03, and the pointer gives an indication of the instantaneous value of the moisture content for this cycle.

The cam 60 and the contacts 93 and 64 may be used to actuate a control system when this moisture content exceeds or is reduced below a predetermined value, or the pilot lights 2|| and 2|2 may be selectively actuated to indicate that the moisture content has risen too high or fallen too low. Thereupon, suitable control may be effected by the operator.

A speciilc embodiment of the invention has been shown for purposes of illustration only, and it is to be understood that the invention may be applied to various uses and that changes and adaptations -may be made therein as will be readily apparent to a person skilled in the art. The invention has been described speciiically as applied to a Slasher. The web |26 may, however, constitute any flexible non-conducting web, the moisture content of which is to be measured, such as a. cellophane web or other cellulosic or fibrous material.

The impulse timer of this invention is described and claimed in my copending application filed May 14, 1949, Serial No. 93,321.

Since it is obvious that many changes and modifications can be made in the above-described details without departing from the nature and spirit of the invention, it is to be understood that the invention is not to be limited thereto except as set forth in the appended claims.

I claim:

l. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession, a condenser, a direct voltage source, means connecting said source in series circuit with said condenser and with said members so that the electrical resistance of the web between said members controls the rate of charge of said condenser, means responsive to the condenser voltage to discharge said condenser when its charge reaches a predetermined value whereby the condenser repeatedly charges and discharges in a cycle the frequency of which is a function of the moisture content of the web, and means responsive to said condenser and measuring said frequency.

2. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession, a condenser, a direct voltage source, means connecting said source in series circuit with said condenser and with said members so that the electrical resistance of the web between said members controls the rate of charge of said condenser, means responsive to the condenser voltage to discharge said condenser when its charge reaches a predetermined value whereby the condenser repeatedly charges and discharges in a cycle the frequency of which is a vfunction of the moisture content of the web, and counter means responsive to said condenser and connected to count said cycles over a predetermined period of time.

3. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession, a condenser, a direct voltage source, means connecting said source in series circuit with said condenser and with said members so that the electrical resistance of the web between said members controls the rate of charge of said condenser, means responsive to the condenser voltage to discharge said con- :,cosms denser when its charge reaches a predetermined value whereby the -condenser repeatedly charges and discharges in a cycle the frequency of which is .a function of the moisture content of the web.

. counter means responsive to said condenser and connected to count said cycles, and timed means to render said counter means inoperative after a Y predetermined time interval.

4. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession, a, condenser, a direct voltage source, means connecting said source in series circuit with said condenser and with said l members so that the electrical resistance of the sive to the running of said webto interrupt the running of said timed means when said web is stopped.

5. A moisture measuring system for devices conducting members insulated from each other over which the web is passed in succession, a. con- "denser, a direct voltage source, means connecting said source in series circuit with said condenser and with said members so that the electrical resistance of the web between said members controls the rate of charge of said condenser, means responsive to the condenser voltage to discharge said condenser when its lcharge said timed means and to interrupt said series charging circuit when said device is stopped.

` j 6. A moisture measuring system for traveling webs, comprising apair of conducting members insulated from each other over which the web is passed in succession, a condenser, a, direct voltage source, means connecting said source in series circuit with said condenser and with said mem- A bers so that the electrical resistance of the web between said members controls the rate of charge of said condenser, means responsive to the condenser voltage to discharge said condenser when its charge reaches a predetermined value whereby the condenser repeatedly charges and discharges in a cycle of the frequency of which is a vfunction ofthe moisture content of the web,

counter means responsive to said condenser and connected to count said cycles, timed means to render said counter means inoperative after apredetermined time interval, reset means for said counter, and means actuated by said reset means to reset said timed means to its initial starting position.

passed in succession, 9, condenser, a direct voltage source, means connecting said source in series circuit with ,said condenser and with said members so that the electrical resistance of the web between said members controls the rate of charge of said condenser, means responsive to the condenser voltage to discharge said condenser when its charge reaches apredetermined value whereby the condenser repeatedly charges and discharges in a cycle the frequency of which is a function of the moisture content of the .web,a relay responsive to operation of the condenser discharge means, a, counter having an electrical actuating coil and means responsive to the actuation of said relay to energize said counter'coil whereby said counter registers the number of said cycles.

8. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession, a condenser, a direct voltage source, means connecting said source in carrying a traveling web, comprising a pair of series circuit with said condenser and with said ymembers so that the electrical resistance of the web between said members controls the rate of charge of said-condenser, means responsive to the condenser voltage to discharge said condenser when its charge reaches a predetermined value whereby the condenser repeatedly charges and discharges in a cycle the frequency of which is a function of the moisture content of the web, a relay responsive to the operation of the condenser discharge means, a step-by-step relay in- 7. A moisture measuring system for traveling cluding an actuating coil, means connecting said actuating coil to respond to the operation of said relay, a counter having an'electrical actuating coil, and means connecting said last coil to be energized by said step-by-step relay whereby said counter registers the number of said cycles.

9. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession, a condenser, a direct voltage source, means connecting said source in series circuit with said condenser and with said members so that the electrical resistance of the web between said members controls the rate of charge of said condenser, a space discharge tube having its space current path connected in said series circuit and having a cathode and a control grid, means connecting said condenser between said cathode and said control grid to apply a negative bias to said grid proportional to the charge on said condenser, a relay having a coil connected in said series circuit and having normally closed contacts connected to discharge'said condenser when the bias reaches cut-off value and interrupts current flow through saidcoil, whereby the condenser repeatedly charges and discharges in a cycle the frequency of which is a function of the moisture content of the web, and means responsive to said condenser and measuring said frequency.

v 10. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession, a, condenser, a direct voltage source, means connecting said source in series circuit with said condenser and with said members so that the electrical resistance of the web between said members controls the rate of charge of said condenser, means responsive to the condenser voltage to discharge said condenser when its charge reaches a predetermined value whereby the condenser repeatedly charges and disl1 A chargesinacyclethefrequencyofwhichisa function of the moisture content oi the web, a timer connected to time the period oi each cycle, and a registering device to register the time o! the last timed interval.

11. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession, a condenser, a direct voltage source, means connecting said source in series circuit with said condenser and with said members so that the electrical resistance oi' the web between said members controls the rate oi' charge ot said condenser, means responsive to the condenser voltage to discharge said condenser when its charge reaches a predetermined value whereby the condenser repeatedly charges and discharges in a cycle the frequency of which is a function of the moisture content oi' the web, a step-bystep relay connected to be actuated in response to actuation oi said condenser discharge means and to alternately open land close a contact, a timer connected to time the interval between successive actuations of said contact, and indicator means to indicate the duration of the last timed interval.

12. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession, a condenser, a direct voltage source, means connecting said source 4in series circuit with said condenser and with said members so that the electrical resistance oi the web between said members controls the rate of charge of said condenser, means responsive to the condenser voltage to discharge said condenser when its charge reaches a predetermined value whereby the condenser repeatedly chargesA and discharges in a cycle the frequency of which is a function of the moisture content of the web, a timer having a driving arm, timed drive means for said arm, a clutch to connect said arm to be driven by said drive means, spring means to reset said arm when said clutch is released, a contact arm driven by said driving arm and having a contact closed by contact with said driving arm, a brake to hold said contact arm in position, spring means to reset said contact arm when said brake is released, a relay connected to be actuated by said condenser discharge means, means responsive to actuation of said relay to release said brake, means responsive to closing of the contact on said contact arm t interrupt said timer and release said clutch 12 for retting said-driving arm andor resetting said brake whereby said contact arm remains at the furthest point reached by said driving arm. 13. A moisture measuring system for traveling webs, comprising a pair of conducting members insulated from each other over which the web is passed in succession. a condenser, a direct voltage source, means connecting said source in lseries circuit with said condenser and with said members so that the electrical resistance oi' the web between said members controls the rate of charge of said condenser. means responsive to the condenser voltage to discharge said condenser when its charge reaches a predetermined value whereby the condenser repeatedly charges and discharges in a cycle the frequency of which is a function of the moisture content of the web, a timer having a driving arm, timed drive means for said arm, a clutch to connect said arm to be driven by said drive means, spring means to reset said arm when said clutch is released, a contact arm driven by said driving arm and having a contact closed by contact with said driving arm, a brake to hold said contact arm in position, spring means to reset said contact arm when said brake is released, a relay connected to be actuated by said condenser discharge means, means responsive to actuation of ysaid relay to release said brake, means responsive to closing of the contact on said contact arm to interrupt said timer and release said clutch for resetting said driving arm and for resetting said brake whereby said contact arm remains at the furthest point reached by said driving arm, and means responsive to closing of said last contacts prior to actuation of said relay to prevent release of said brake whereby the contact arm is driven to a new position by said driving arm and remains in its last position when said driving arm is reset.

JOHN S. SENEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,212,014 Butts J n. 9, 1917 1,623,436 Peschl Apr. 5, 1927 1,890,545 Limbrick Dec. 13, 1932 2,171,363 Gulliksen Aug. 29, 1939 2,317,538 Lamar Apr. 27, 1943 

